1. Field of Invention
The present invention relates to a mask pattern and method for forming the same. More particularly, the present invention relates to a mask pattern having a continuous pattern and method for forming the same.
2. Description of Related Art
As the integrated circuit is highly developed, the reduction and integration of the device become an inevitable tendency and are the main development task for the industry. In the manufacturing process of the integrated circuit, the photolithography process becomes a primary key for determining the device properties.
With the increasing of the integration of the device, the size of the device is reduced and the distance between the devices is reduced as well. Therefore, the deviation occurs as the pattern is transferred from the mask to the material layer in the photolithography process. That is, when a pattern on a mask is transferred onto a wafer by using the photolithography process, the corner rounding and end-cap shortening usually happen on the transferred pattern and the line width of the pattern is either increased or decreased. This kind of phenomenon is so-called optical proximity effect (OPE).
The deviation is relatively small when the size of the device is large and the integration of the device is low. Nevertheless, in the integrated circuit with high integration, the device properties are seriously affected. For example, in the integrated circuit with high integration, the distance between the devices is small and, when the line width of the transferred pattern is expanded, it is highly possible that some of the patterns/features are bridging each other so that a short circuit happens. Therefore, the electrical performance of the device is seriously affected.
In order to overcome the pattern distortion problem occurring while the pattern is transferred, the United States patent under the U.S. Pat. No. 6,673,638 and the United States published application under the published application number 2006/0046160 mention to additionally form assistant patterns between the device patterns on the mask so that the phenomenon of the end-cap shortening and the corner rounding occurring during the device pattern transferred can be reduced by utilizing the optical effect. However, additionally forming the assistant pattern would complicate the patterns on the mask. Also, with the increased number of the corners of the assistant pattern, the storage space of the database for storing the date for designing the mask pattern is increased.